Methods and systems for communicating between base stations of two different wireless communication networks

ABSTRACT

A method for communicating between base stations of two different wireless communication networks may include (1) transmitting a setup request message from a first base station of a first wireless communication network to a second base station of a second wireless communication network, the setup request message including a first user equipment (UE) device context format of the first wireless communication network and a second UE device context format of the second wireless communication network; (2) receiving, at the first base station, a setup response from the second base station, the setup response including a union of the first UE device context format and the second UE device context format; and (3) at the first base station, communicating with the second base station according to the union of the first UE device context format and the second UE device context format.

RELATED APPLICATIONS

This application claims benefit of priority of U.S. Provisional PatentApplication Ser. No. 62/642,956, filed on Mar. 14, 2018, which isincorporated herein by reference.

BACKGROUND

User Equipment (UE) devices, such as mobile telephones and tabletcomputers, may move or “roam” from one wireless communication network toanother, such as when moving from one geographic area to anothergeographic area, or due to changes in wireless communication service.For example, a UE device moving from a first geographic area to a secondgeographic area may roam from a first wireless communication networkcovering the first geographic area to a second wireless communicationnetwork covering the second geographic area. As another example, a UEdevice may roam from a first wireless communication network to a secondwireless communication network covering the same geographic area inresponse to degraded service from the first wireless communicationnetwork. This ability of a UE device to roam among wirelesscommunication networks helps ensure that the UE device has qualityservice available as the UE device moves to different geographic areasand as wireless communication service changes in quality.

In addition, new technologies are expected to increase the number ofwireless communication networks available in many areas. For example,multiple wireless communication service providers may establishrespective wireless communication networks in a common area using sharedradio frequency (RF) spectrum, e.g., in citizens broadband radio service(CBRS) spectrum or in unlicensed spectrum, operating according toaspects of a long-term evolution (LTE) protocol or a fifth generation(5G) New Radio-Unlicensed (NR-U) protocol. As another example, siteoperators may establish neutral host networks, e.g. LTE networks or 5GNR-U networks, that are open to subscribers of multiple wirelesscommunication service providers, to improve wireless communication attheir respective sites. Such increase in wireless communication networksmay increase opportunities for UE devices to roam among wirelesscommunication networks.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating two wireless communicationnetworks configured to support communication between respective basestations of the two wireless communication networks, according to anembodiment.

FIG. 2 is a schematic diagram of a central control device, according toan embodiment.

FIG. 3 is a schematic diagram of another central control device,according to an embodiment.

FIG. 4 is a schematic diagram of a base station of a wirelesscommunication system, according to an embodiment.

FIG. 5 is a schematic diagram of another base station of a wirelesscommunication system, according to an embodiment.

FIG. 6 is a flow chart illustrating a method for communicating betweenbase stations of two different wireless communication networks,according to an embodiment.

FIGS. 7A-7C collectively form a timing diagram illustrating a method forestablishing a communication interface between two base stations ofdifferent respective wireless communication networks, according to anembodiment.

FIG. 8 is a flow chart illustrating a method for coordinating a handoverof a UE device between respective base stations of two differentwireless communication networks, according to an embodiment.

FIGS. 9A-9C collectively form a timing diagram illustrating anothermethod for coordinating a handover of a UE device between respectivebase stations of two different wireless communication networks,according to a network.

FIGS. 10A-10C collectively form a timing diagram illustrating yetanother method for coordinating a handover of a UE device betweenrespective base stations of two different wireless communicationnetworks, according to a network.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Disclosed herein are methods and systems for communicating between basestations of two or more different wireless communication networks. Insome embodiments, the different wireless communication networks sharecommon RF spectrum, e.g. CBRS spectrum or unlicensed spectrum. Inparticular embodiments, respective base stations of different wirelesscommunication networks are capable of establishing communicationinterfaces between each other, such that the base stations of thedifferent wireless communication networks can communicate with eachother. The base stations of the different wireless communicationnetworks communicate with each other, for example, to coordinatehandover of a UE device from one base station to another, to coordinatesharing of common RF spectrum, and/or to help prevent interferencebetween base stations. In some embodiments, the base stations coordinatesharing of common RF spectrum, e.g., at least partially according tobase station load and/or market conditions.

FIG. 1 is a schematic diagram illustrating two wireless communicationnetworks 102 and 104 that are configured to support communicationbetween respective base stations of the two wireless communicationnetworks. Wireless communication network 102 includes a central controldevice 106 and a base station 108, and wireless communication network104 includes a central control device 110 and a base station 112. Eachof central control device 106 and central control device 110 controlsoperation of at least some aspects of its respective wirelesscommunication network 102 and 104. In some embodiments, each of centralcontrol device 106 and central control device 110 includes a packet corenetwork, e.g. an evolved packet core (EPC), an extension of an EPC, a 5GCore, a Wireless-Wireline Converged Core, a Wi-Fi Core, or a variationof an EPC. Although central control devices 106 and 110 are eachdepicted as a single device in FIG. 1, central control devices 106 and110 may include a plurality of elements, which may be located togetheror may be distributed among two or more locations. Central controldevice 106 and central control device 110 need not necessarily have thesame configuration, for example, based on one of the eight split optionsdescribed by the ITU-T and 3GPP.

Each of base station 108 and base station 112 provides wireless accessto its respective wireless communication network 102 and 104 for one ormore UE devices. For example, FIG. 1 illustrates a UE device 114 beingconnected to base station 108 via RF signals 116. In some embodiments,RF signals 116 are within unlicensed RF spectrum, e.g., CBRS spectrum orWi-Fi spectrum, and wireless communication networks 102 and 104 sharethe spectrum. In some other embodiments, wireless communication networks102 and 104 operate with different respective RF spectrum. Examples ofeach of base station 108 and 112 include, but are not limited to, a LTEbase station (e.g., an eNB device), a NR base station (e.g., a gNBdevice), a sixth Generation (6G) wireless communication base station, aWi-Fi base station (e.g., including unscheduled, partially scheduled,and unscheduled systems), and variations and/or extensions thereof.Examples of UE device 114 include, but are not limited to, a computer, aset-top device, a data storage device, an Internet of Things (IoT)device, an entertainment device, a wireless access point (including, forexample, eNBs, gNBs, and Wi-Fi APS acting as UEs), a computer networkingdevice, a mobile telephone, a smartwatch, a wearable device withwireless capability, and a medical device. In some embodiments, each ofbase station 108, base station 112, and UE device 114 operate accordingto a LTE protocol, a 4G protocol, a NR protocol, e.g., a 5G protocol, aNew Radio-Unlicensed (NR-U) protocol, or a 6G protocol.

Each of wireless communication network 102 and wireless communicationnetwork 104 may include additional base stations (not shown), such as toprovide wireless service over a significant geographic area or to covermore than one wireless communication protocol. Additionally, althoughonly one UE device 114 is illustrated in FIG. 1 for simplicity, it isanticipated (but not required) that each of wireless communicationnetwork 102 and wireless communication network 104 will serve multipleUE devices at a given time.

Base station 108 is communicatively coupled to central control device106 via a communication interface 118, and base station 112 iscommunicatively coupled to central control device 110 via acommunication interface 120. Each of communication interface 118 andcommunication interface 120 includes, for example, one or more of anoptical cable, an electrical cable, and a wireless communication link.In some embodiments, each of communication link 118 and communicationlink 120 is an evolved packet system interface, e.g. a superset of aS1-U interface and S1-MME interface.

Central control device 106 and central control device 110 arecommunicatively coupled via a communication link 112. In someembodiments, communication link 112 includes a dedicated communicationlink between wireless communication network 102 and wirelesscommunication network 104. In some embodiments, communication link 112includes a non-dedicated communication link, e.g., the public Internet.Communication link 112 could include multiple communication circuits,e.g., a dedicated optical cable operating in conjunction with the publicInternet or via one or more access networks directly or indirectlyconnected, etc. Although wireless communication networks 102 and 104 aredepicted as having a common architecture, the architectures of wirelesscommunication networks 102 and 104 need not be the same. For example, insome embodiments, wireless communication networks 102 and 104 are ownedby different respective wireless communication service providers andhave different respective architectures.

FIGS. 2 and 3 illustrate one possible embodiment of central controldevice 106 and central control device 110, respectively. It should beappreciated, however, that control device 106 and central control device110 are not limited to the embodiments of FIGS. 2 and 3 or even to anEPC. To the contrary, central control device 106 and central controldevice 110 could have essentially any configuration as long as theysupport communication between base stations 108 and 112, communicationbetween systems or entities that control (directly or indirectly) basestations 108 and 112, or system or entities that facilitatecommunication between base stations 108 and 112, as discussed below.

FIG. 2 is a schematic diagram of a central control device 200, which isone embodiment of central control device 106 of FIG. 1 configured as anEPC. Central control device 200 includes a PDN Gateway (P-GW) 202, aPolicy Control and Charging Rules Function (PCRF) 204, a Serving Gateway(S-GW) 206, a Mobility Management Entity (MME) 208, and a HomeSubscriber Server (HSS) 210. P-GW 202 is communicatively coupled to PCRF204 via an interface Gx, and P-GW 202 is communicatively coupled to S-GWvia an interface S5/S8. MME 208 is communicatively coupled to S-GW 206via an interface S11, and MME 208 is communicatively coupled to HSS 210via an interface S6a. MME 208 and S-GW 206 are communicatively coupledto base station 108 via interfaces S1-MME and S1-U, respectively. In theevent wireless communication network 102 includes additional basestations (not shown), interfaces S1-MME and S1-U are communicativelycoupled to each base station. Two or more elements of central controldevice 200 could be combined without departing from the scope hereof.Additionally, central control device 200 could include additionalelements. For example, in some embodiments, central control device 200includes multiple instances of MME 208 forming a pool of MMES. Inparticular embodiments, the elements of control device 200 areimplemented by one or more processors (not shown) executing instructionsstored in one or more memories (not shown).

PCRF 204, for example, performs policy control decision making andcontrols flow-based charging in a Policy Control Enforcement Function(PCEF) (not shown) in P-GW 202. In some embodiments, PCRF 204 alsoperforms Quality of Service (QoS) authorization to determined how dataflow is handled in P-GW 202. PCRF 204 is communicatively coupled to IPServices 212 via an interface Rx. IP Services 212 include servicesavailable to subscribers of wireless communication network 102 that arenot part of wireless communication network 102.

In particular embodiments, P-GW 202 allocates Internet Protocol (IP)addresses to UE devices (e.g., UE device 114) and enforces QoS andflow-based charging according to PCRF 204. P-GW 202 may also filterdownlink user IP packets into different QoS-based bearers fortransmission to UE devices. P-GW 202 is communicatively coupled to IPServices 212 via a SGi interface. In some embodiments, S-GW 206transfers user IP packets from central control device 200 to basestation 108 (an any additional base stations in wireless communicationnetwork 102). S-GW 206 also, for example, (a) retains information aboutbearers when an UE device is in its idle state, (b) temporarily buffersdownlink data while MME 208 pages the UE device to re-establish bearers,and (c) perform administrative functions associated with a visiting UEdevice in wireless communication network 102.

MME 208, for example, processes signaling between central control device200 and UE devices (e.g., UE device 114). In certain embodiments, MME208 handles establishment, maintenance, and release of bearers, as wellas connection and security management. In some embodiments, HSS 210houses subscriber data, such as subscriber QoS profiles and subscriberroaming permissions, as well as dynamic subscriber information, such asidentity of a MME that a UE device 104 is connected to.

Central control device 300 is communicatively coupled between IPServices 312 and base station 112. Central control device 300 includes aP-GW 302, a PCRF 304, a S-GW 306, a MME 308, and a HSS 310, which areanalogous to P-GW 202, PCRF 204, S-GW 206, MME 208, and HSS 210,respectively.

FIGS. 4 and 5 illustrate one possible embodiment of base station 108 andbase station 112, respectively. It should be appreciated, however, thatbase station 108 and base station 112 are not limited to the embodimentsof FIGS. 4 and 5. Instead, base stations 108 and 112 could haveessentially any configuration as long as they support communicationbetween themselves, as discussed below.

FIG. 4 is a schematic diagram of a base station 400, which is oneembodiment of base station 108. Base station 400 includes a processor402, a memory 404, a transceiver 406, and an antenna 408. Processor 402is configured to execute instructions 410 stored in memory 404 tocontrol base station 400. Transceiver 406 is communicatively coupled toantenna 408, and transceiver 406 interfaces antenna 408 with othercomponents of base station 400. For example, in some embodiments,transceiver 406 converts electrical signals generated by processor 402into RF signals for transmission to UE devices via antenna 408, andtransceiver 406 converts RF signals received from UE devices via antenna408 into electrical signals for processor 402. One or more elements ofbase station 400 may include multiple sub-elements. For example,processor 402 could include a plurality of sub-processors, memory 404could include a plurality of memory modules, and antenna 408 couldinclude multiple radiating/receiving elements. Additionally, processor402 and memory 404 could be replaced with other circuitry, e.g. analogand/or digital electronic circuitry, performing similar functions toprocessor 402 and memory 404. Furthermore, although base station 400 isillustrated as being a self-contained device, two or more elements ofbase station 400 could be distributed among multiple locations. Forexample, processor 402 and memory 404 could be located at a differentlocation than transceiver 406 and antenna 408. Moreover, multipleinstances of base station 400 could share one or more elements withoutdeparting from the scope hereof.

FIG. 5 is a schematic diagram of a base station 500, which is oneembodiment of base station 112. Base station 500 includes a processor502, a memory 504, a transceiver 506, and an antenna 508, which areanalogous to processor 402, memory 404, transceiver 406, and antenna408, respectively. Processor 502 is configured to execute instructions510 stored in memory 504 to control base station 500, in a mannersimilar to that discussed above with respect to FIG. 4. One or moreelements of base station 500 may include multiple sub-elements. Forexample, processor 502 could include a plurality of sub-processors,memory 504 could include a plurality of memory modules, and antenna 508could include multiple radiating/receiving elements. Additionally,processor 502 and memory 504 could be replaced with other circuitry,e.g. analog and/or digital electronic circuitry, performing similarfunctions to processor 502 and memory 504. Furthermore, although basestation 500 is illustrated as being a self-contained device, two or moreelements of base station 500 could be distributed among multiplelocations. For example, processor 502 and memory 504 could be located ata different location than transceiver 506 and antenna 508. Moreover,multiple instances of base station 500 could share one or more elementswithout departing from the scope hereof.

Referring again to FIG. 1, base stations 108 and 112 are collectivelyconfigured to establish a communication interface 122 between eachother, to allow base stations 108 and 112 to communicate with eachother. In some embodiments, communication interface 122 includes adedicated communication link between base station 108 and 112 (e.g. anoptical communication link and/or a RF communication link), and in someembodiments, communication interface 122 is a logical interface thatdoes not require a direct connection between base station 108 and basestation 112. In certain embodiments, communication interface 122 enablesbase stations 108 and 112 to communicate with each other with minimal orno assistance from central control devices 106 and 110 or any otherintermediary, which advantageously promotes low-latency communicationbetween base stations 108 and 112. In particular embodiments, basestations 108 and 112 use communication interface 122 for one or more of(a) coordinating a handover of UE device 114 from base station 108 tobase station 112 (or vice versa) and (b) coordinating use of RF spectrumshared by base stations 108 and 112 to prevent interference between thetwo base stations and/or to help optimize use of shared RF spectrum. Insome embodiments, base stations 108 and 112 use communication interface122 multiple times after it is established.

In this document, communication between base stations, e.g., betweenbase stations 108 and 112, includes but is not limited to communicationbetween respective Internet Protocol (IP) layers of the base stations.In embodiments where a base station 108 or 112 is a remote base station(e.g., a remote small cell), the base station's respective IP layer isoptionally located at a central base station (e.g., a central cell).

In certain embodiments, base stations 108 and 112 execute a method 600of FIG. 6 to establish communication interface 122 and to communicatebetween the base stations. For example, in embodiments where basestations 108 and 112 are respectively embodied by base stations 400 and500, processor 402 executes instructions 410 and processor 502 executesinstructions 510, to execute method 600. In block 602 of method 600,base station 108 transmits a setup request message to base station 112.The setup message request includes, in part, a first UE device contextformat and a second UE device context format. The first UE devicecontext format represents how a UE device context is represented inwireless communication network 102, and the second UE device contextformat represents how a UE device context is represented in wirelesscommunication network 104. Base station 108 obtains the first UE devicecontext format and the second UE device context format, for example,from central control device 106.

In block 604, base station 112 receives the setup request message frombase station 108. In block 606, base station 112 transmits a setupresponse to base station 108. The setup response includes a union of thefirst UE device context format and the second UE device context format.Each of the first UE device context format and the second UE devicecontext format includes one or more respective information fields. Somepossible examples of UE device context information fields include, butare not limited to, UE device status, UE device type, UE devicelocation, UE device connections (e.g., UE device data bearers), evolvedpacket system (EPS) security context (e.g., security keys, securitymode), authentication quadruplets or quintuplets, UE device networkcapabilities, PDN connection information, EPS bearer identification,Internet Protocol (IP) address, and/or aggregate maximum bit rate(AMBR). As one example of the union of UE device context formats, assumea scenario where the first UE device context format includes informationfields A, B, and C, and the second UE device context format includesinformation fields A, C, and D. The union of the first UE device contextformat and the second UE device context format includes informationfields A, B, C, and D, i.e., a superset of the information fields of thetwo UE device context formats. In block 608, base station 108 receivesthe setup response from second base station 112.

In block 610, base stations 108 and 112 communicate with each otheraccording to the union of the first UE device context format and thesecond UE device context format. For example, in some embodiments, basestation 108 includes data for all information fields of the union of UEdevice context formats when sending a message to base station 112, andbase station 112 includes data for all information fields of the unionof UE device context formats when sending a message to base station 108.Such inclusion of all information fields of the union in messages sentbetween base station 108 and base station 112 advantageously enables thetwo base stations to communicate with each other if the two basestations use different UE device context formats.

FIGS. 7A-7C collectively illustrate an example of a method forestablishing a communication interface between base stations of twodifferent wireless communication networks. For example, the method ofFIGS. 7A-7C may be used to establish interface 122 between base stations108 and 112 in an embodiment where central control devices 106 and 110are embodied as illustrated in FIGS. 2 and 3, respectively. Accordingly,the method FIGS. 7A-7C is one embodiment of method 600 of FIG. 6. Inembodiments where base stations 108 and 112 are respectively embodied bybase stations 400 and 500, processor 402 executes instructions 410 andprocessor 502 executes instructions 510, to execute the methodillustrated in FIGS. 7A-7C. In the example of FIGS. 7A-7C, the basestations are eNBs. For example, the source eNB may be base station 108configured as an eNB, and the target eNB may be base station 112configured as an eNB. Additionally, the source MME may be MME 208, andthe target MME may be MME 308. However, the method of FIGS. 7A-7C couldbe adapted for use with a different type of base stations, e.g., gNBbase stations, as well as for different central control deviceconfigurations. In FIGS. 7A-7C, vertical axis 702 represents time, andvertical lines 704, 706, 708, and 710 logically represent the sourceeNB, the target eNB, the source MME, and the target MME, respectively.

The method of FIGS. 7A-7C begins with the source eNB transmitting a handover request message 712 to the source MME. Message 712 is transmittedaccording to a S1 interface application protocol (AP), e.g., over theS1-MME interface of FIG. 2, and message 712 advises the source MME thatthe source eNB wishes to initiate a handover of a UE device (e.g., UEdevice 114) from the source eNB to the target eNB. Message 712 includesidentity of the target eNB and the identity of the visited wirelesscommunication network (e.g., wireless communication network 104), whichis sometimes referred to as a Public Land Mobile Network (PLMN).

The source eNB next sends a eNB-Config-Transfer message 714 to thesource MME using a S1 AP, e.g., over the S1-MME interface of FIG. 2.Message 714 again includes identity of the target eNB and the visitedPLMN. Message 714 additionally includes a SON-Information-Request and aY3-Config-Info request. The SON-Information-Request is, for example, aSON-Information-Request specified in LTE standards or in similarstandards, where SON refers to self-optimizing networks. TheY3-Config-Info is information needed to establish an interface betweenbase stations of two different wireless communication networks (e.g.,interface 122 between base stations 108 and 112). This interface isreferred to as “Y3” for brevity, although it should be understood thatuse of term Y3 is not intended to restrict the interface to anyparticular protocol, physical layer configuration, or wirelesscommunication standard. One example of a Y3 interface is interface 122of FIG. 1.

The source MME next sends a MME-Config-Transfer-Request message 716 tothe target MME, e.g., using interface 112 of FIG. 1. Message 716includes, for example, the same information included in message 714.FIG. 7A illustrates one example of Y3-Config-Info in message 716. Inthis example, Y3-Config-Info includes the following information,although the content of Y3-Config-Info may vary without departing fromthe scope hereof: (a) Rx-Y3-Transport Layer Addresses, (b) Rx-UEContext-Format-V, (c) Tx-PGW-S8-Address, (d) Tx-Hss Sha-Address, (e)Tx-AGW-TrGW-Address, and (f) Tx-P-CSCF-Address. Rx-Y3-Transport LayerAddresses is a request for transport layer addresses associated with thetarget eNB, and Rx-UE Context-Format-V is a request for the UE devicecontext format of the visited wireless communication network (e.g., thesecond UE device context format discussed above with respect to FIG. 4).Tx-PGW-S8-Address is a notification of the address of the source P-GW(e.g., P-GW 210), and Tx-Hss S6a-Address is a notification of theaddress of the source HSS (e.g., HSS 210). Tx-AGW-TrGW-Address is anotification of the address of the source access gateway, which includesaddresses of the source S-GW and P-GW (e.g., S-GW 206 and P-GW 202).Tx-P-CSCF-Address is a notification of an address of a call sessioncontrol function (CSCF) of the home network (e.g., wirelesscommunication network 102).

The target MME sends a MME-Config-Transfer-Reply message 718 to thesource MME (FIG. 7B). Message 718 confirms the target eNB identity andthe visited PLMN identity. Message 718 additionally provides theSON-Information Request to the home wireless communication network.Furthermore, message 718 includes at least some Y3-Config-Info. In theillustrated example, message 718 includes the following Y3-Config-Info,although the content of Y3-Config-Info in message 718 may vary withoutdeparting from the scope hereof: (a) Tx-Y3-Transport Layer Addresses,(b) Tx-UE Context-Format-V, and (c) Tx-HR-vs-LBO. Tx-Y3-Transport LayerAddresses is notification of the address of the target eNB, Tx-UEContext-Format-V is notification of the UE device context format ofvisited wireless communication network, and (c) Tx-HR-vs-LBO isnotification of whether the visited wireless network prefers homerouting (HR) or local break-out (LBO) operation. HR refers to when a UEon a visited network uses the P-GW of its home network, and LBO refersto when a UE on a visited network use the P-GW of the visited network.

Source MME 720 transmits a MME-Config-Transfer message 720 to the sourceeNB. Message 720 is similar to message 718 but withInter-Network-Config-Info replacing Y3-Config-Info. In the illustratedexample, message 720 includes the following Inter-Network-Config-Info,although the content of Inter-Network-Config-Info in message 720 mayvary without departing from the scope hereof: (a) Tx-Y3-Transport LayerAddresses, (b) Tx-UE Context-Format-V.

The source eNB is ready to negotiate the Y3 interface after receivingmessage 720 from the source MME. Accordingly, the source eNB transmits aY3AP-Setup-Request message 722 to the target eNB using a Y3 AP. In someembodiments, the Y3 AP includes a message set needed to establish the Y3AP and defining what can be communicated across the Y3 interface. Inparticular embodiments, message 722 includes notification of the sourceeNB's identity (Tx-Source eNB Identity) and Y3-Configuration-Info. Inthe illustrated example, message 722 includes the followingY3-Config-Info, although the content of Y3-Config-Info in message 722may vary without departing from the scope hereof: (a) Tx-Served CellsInfo, (b) Tx-UE-Context-Format-H, and (c) Tx-Ack-UE-Context-Format-V.Tx-Served Cells Info is notification of cells served by the source eNB,and Tx-UE-Context-Format-H is UE context format of the home wirelesscommunication network (including the source eNB).Tx-Ack-UE-Context-Format-V is an acknowledgement from the source eNBthat it is aware of the visited network's UE context format.

The target eNB responds to message 722 by sending a Y3AP-Setup-Responsemessage 724 using the Y3 AP to the source eNB (FIG. 7C). Message 724includes, for example, notification of the target eNB's identity(Tx-Target eNB Identity) and Y3-Configuration-Info. In the illustratedexample, message 724 includes the following Y3-Config-Info, although thecontent of Y3-Config-Info in message 724 may vary without departing fromthe scope hereof: (a) Tx-Served Cells Info, (b)Tx-Ack-UE-Context-Format-H, and (c) Tx-UE-Context-Format-U. Tx-ServedCells Info is notification of cells served by the target eNB, andTx-Ack-UE-Context-Format-H is an acknowledgement from the target eNBthat it is aware of the home network's UE context format.Tx-UE-Context-Format-U is the union of UE-Context-Format-H andUE-Context-Format-V, i.e., the union of the UE device context format ofthe home network and the UE device context format of the visitednetwork.

Receipt of message 724 by the source eNB concludes negotiation of the Y3interface between the source eNB and the target eNB. The two eNBs cansubsequently use the interface to communicate, e.g., to coordinatehandover of a UE device and/or to coordinate use of shared RF spectrum.The two eNBs use UE-Context-Format-U when communicating with respect toa UE, to enable such communication in cases where the home and visitednetworks use different UE context formats.

The source eNB sends a handover cancel message 726 to the source MMEafter receipt of message 724, to cancel the S1 handover initiated bymessage 712, using a S1 AP. Message 726 includes identity of thetargeted eNB and the visited PLMN.

FIG. 8 is a flow chart illustrating a method 800 for coordinatinghandover of a UE device between base stations 108 and 112. Method 800 isperformed, for example, after interface 122 is established between thetwo base stations, e.g., using the method of FIG. 6 or the method ofFIGS. 7A-7C. In embodiments where base stations 108 and 112 arerespectively embodied by base stations 400 and 500, processor 402executes instructions 410 and processor 502 executes instructions 510,to execute method 800.

In block 802, base station 108 transmits a handover request to basestation 112 using interface 122 between base station 108 and basestation 112, and base station 112 receives the handover request in block804. Base station 112 transmits a handover confirmation request to basestation 108 in block 806, in response to receiving the handover requestin block 804. Base station 108 receives the handover confirmationmessage in block 808, and base station 108 responds by transmitting ahandover command message to UE device 114 in block 810. The handovercommand message commands UE device 114 to disconnect from base station108 and connect to base station 112.

Base station 112 transmits a path switch request to central controldevice 110 in block 812. The path switch requests instructs centralcontrol device 110 to direct data associated with UE device 114 to basestation 112, since UE device 114 is connected to base station 112 afterbase station 108 transmits the handover command message to UE device114. In block 814, base station 108 relays data associated with UEdevice 114 between first central control device 106 and base station112, during the handover. In block 816, second base station 112 relaysdata between first base station 108 and base station 112, during thehandover.

Although FIG. 8 illustrates blocks 802-816 being disposed in a linearsequence, these blocks need not necessarily be executed in theillustrated sequence. For example, blocks 810 and 812 could be executedin parallel, or block 812 could be executed before block 810.

FIGS. 9A-9C collectively illustrate an example of a method forcoordinating handover of a UE device between base stations of differentwireless communication networks using home routing. Accordingly, themethod of FIGS. 9A-9C is one embodiment of method 800 of FIG. 8. Inembodiments where base stations 108 and 112 are respectively embodied bybase stations 400 and 500, processor 402 executes instructions 410 andprocessor 502 executes instructions 510, to execute the methodillustrated in FIGS. 9A-9C. In the example of FIGS. 9A-9C, the basestations are eNBs. For example, the source eNB may be base station 108configured as an eNB, and the target eNB may be base station 112configured as an eNB. Additionally, the source MME may be MME 208, thetarget MME may be MME 308, the source S-GW may be S-GW 206, the targetS-GW may be S-GW 306, and the source P-GW may be P-GW 202. However, themethod of FIGS. 9A-9C could be adapted for use with a different type ofbase stations, e.g., gNB base stations, as well as for different centralcontrol device configurations. In FIGS. 9A-9C, vertical axis 902represents time, and vertical lines 904, 906, 908, 910, 912, 914, and916 logically represent a source eNB, a target eNB, a source MME, atarget MME, a source S-GW, a target S-GW, and a source P-GW,respectively.

The method of FIGS. 9A-9C begins with the source eNB transmitting aY3AP-Handover-Preparation message 918, to request handover of a UEdevice, using the Y3 AP. Message 918 includes Tx-Target eNB Identity andTx-UE-Context-Format-U, as discussed above with respect to FIGS. 7A-7C.The source eNB transmits message 918, for example, in response todetermining that the UE device would be better served by the target eNBthan the source eNB. The target eNB responds to message 918 bytransmitting a Y3AP-Handover-Preparation message 920 using the Y3 AP.Message 920 includes (a) Tx-Handover Request Ack, (b)Tx-Handover-Command, and (c) Tx-RRC-Connection-Reconfig. Tx-HandoverRequest Ack is an acknowledgement from the target eNB of the handoverrequest, and Tx-Handover-Command is a command from the target eNB to thesource eNB to begin the handover process. Tx-RRC-Connection-Reconfig isa command to the source eNB to cause the UE device (e.g., UE device 114)to reconfigure its radio resource control (RRC) for operation with thesource eNB. The source eNB sends implements Tx-RRC-Connection-Reconfig,for example, by sending a handover command message from the first basestation to the UE device.

The target eNB next sends a Path-Switch-Request message 922 to thetarget MME via a S1 AP. Message 922 includes, for example, Tx-Source eNBIdentity, Tx-Target eNB Identity, Tx-UE-Identity, andTx-eRAB-ToBeMoved-List. Tx-Source eNB Identity is notification of thesource eNB's identity, Tx-Source eNB Identity is notification of thetarget eNB's identity, and Tx-UE-Identity is notification of the UE'sidentity. Tx-eRAB-ToBeMoved-List is notification of radio bearersassociated with the UE which will need to be handled by the target MME.The source MME next transmits a Modify-Bearer-Request message 924 to theTarget S-GW via a GPRS tunneling protocol (GTP), e.g., via GTPv2,including Tx-F-TEID and Tx-Bearer-Content (FIG. 9B). Tx-F-TEID isnotification of the Fully Qualified Tunnel End Point Identifier(F-TEID), and Tx-Bearer-Content is notification of the characteristicsof the bearers that will need to be handled by the Target S-GW. Thetarget S-GW then sends a Modify-Bearer-Request message 926 to the SourceP-GW via GTPv2, to set-up home routing. In particular embodiments,message 926 includes the same information as message 924.

The source P-GW acknowledges receipt of message 926 by sending aModify-Bearer-Response message 928 to the Target S-GW via GTPv2, and thetarget S-GW in turn sends a Modify-Bearer-Response message 930 to thesource MIME. The target MME then sends a Path-Switch-Response message932 to the target eNB, including Tx-Source eNB Identity, Tx-Target eNBIdentity, Tx-UE Identity, and Tx-eRAB-ToBeMoved-List (FIG. 9C).Tx-Source eNB Identity, Tx-Target eNB Identity, and Tx-UE Identity arethe same as discussed above, and Tx-eRAB-ToBemoved-list is a list ofradio bearers associated with the UE device to be handled by the targeteNB. The UE device is now connected to the target eNB with home routingthrough the source P-GW.

FIGS. 10A-10C collectively illustrate an example of a method forcoordinating handover of a UE device between base stations of differentwireless communication networks using local break-out routing.Accordingly, the method of FIGS. 10A-10C is another embodiment of method800 of FIG. 8. The method of FIGS. 10A-10C is like the method of FIGS.9A-9C except that (a) message 926 is transmitted to the target P-GWinstead of the source P-GW, and (b) message 928 is sent from the targetP-GW instead of the source S-GW. Vertical line 1002 in FIG. 10Blogically represents the target P-GW.

Referring again to FIG. 1, in certain embodiments base stations 108 and112 coordinate use of shared RF spectrum via interface 122, as discussedabove. In some embodiments, base stations 108 and 112 share RF spectrumon a fairness basis. For example, in certain embodiments, the shared RFspectrum is allocated between base stations 108 and 112 in proportion toeach base station's need for the spectrum. Each base station's need forthe spectrum is determined, for instance, based on its respective load,such as indicated by one or more of (1) the base station's radio usagetime, the base station's backhaul usage, and/or the number of UE devicessupported by the base station. For example, consider a scenario wherebase station 108 supports 50 UE devices and base station 112 supports 25UE devices. In this example, base station 108 supports two thirds of thetotal number of UE devices collectively supported by base stations 108and 112, and base stations 108 and 112 are therefore allocated twothirds and one third of the available spectrum, respectively.

In some other embodiments, base stations 108 and 112 share RF spectrumon a market basis. For example, in certain embodiments, each basestation 108 and 112 executes instructions to automatically rent sharedRF spectrum according to market price for RF spectrum rental. Forexample, base station 108 may be programed to rent a first amount ofspectrum if the market price is less than a threshold value, and basestation 108 may be programed to rent a second amount of spectrum if themarket price is greater than or equal to the threshold value. Inparticular embodiments, base stations 108 and 112 automaticallynegotiate use of shared RF spectrum on a market basis according topredetermined rules, without involvement of an intermediary, which mayadvantageously promote fast and low-cost spectrum allocation.

The above-discussed concepts of sharing spectrum according to a fairnessapproach or a market-based approach could be applied to shared resourcesother than RF spectrum. For example, the approaches could be applied toallocation of capacity of an optical cable or an electrical cable sharedby two or more devices.

Features described above may be combined in various ways withoutdeparting from the scope hereof. The following examples illustrate somepossible combinations:

(A1) A method for communicating between base stations of two differentwireless communication networks may include (1) transmitting a setuprequest message from an Internet Protocol (IP) layer of a first basestation of a first wireless communication network to an IP layer of asecond base station of a second wireless communication network, thesetup request message including a first user equipment (UE) devicecontext format of the first wireless communication network and a secondUE device context format of the second wireless communication network,(2) receiving, at the IP layer of the first base station, a setupresponse from the IP layer of the second base station, the setupresponse including a union of the first UE device context format and thesecond UE device context format, and (3) at the IP layer of the firstbase station, communicating with the IP layer of the second base stationaccording to the union of the first UE device context format and thesecond UE device context format.

(A2) The method denoted as (A1) may further include, before transmittingthe setup request message, (1) transmitting a configuration transfermessage from the IP layer of the first base station to a first centralcontrol device of the first wireless network, the configuration transfermessage including a request for the second UE device context format and(2) receiving a configuration transfer response message at the IP layerof the first base station from the first central control device, theconfiguration transfer response message including the second UE devicecontext format.

(A3) In the method denoted as (A2), the configuration transfer messagemay further include an identity of the second wireless communicationnetwork.

(A4) In any one of the methods denoted as (A2) and (A3), theconfiguration transfer message may further include a request for one ormore addresses associated with the second wireless communicationnetwork.

(A5) Any one of the methods denoted as (A2) through (A4) may furtherinclude transmitting the configuration transfer message from the IPlayer of the first base station to a Mobility Management Entity (MME) offirst central control device.

(A6) Any one of the methods denoted as (A1) through (A5) may furtherinclude (1) transmitting a handover request message from the IP layer ofthe first base station to the IP layer of the second base station,according to the union of the first UE device context format and thesecond UE device context format, (2) receiving, at the IP layer of thefirst base station, a handover confirmation message from the IP layer ofthe second base station, and (3) in response to receiving the handoverconfirmation message at the IP layer of first base station, transmittinga handover command message from the IP layer of the first base stationto a UE device connected to the first base station.

(A7) The method denoted as (A6) may further include, at the first basestation, relaying data associated with the UE device between the firstcentral control device and the IP layer of the second base station,during a handover of the UE device from the first base station to thesecond base station.

(A8) Any one of the methods denoted as (A1) through (A7) may furtherinclude operating the first base station in radio frequency (RF)spectrum shared with the second base station.

(A9) The method denoted as (A8) may further include, at the IP layer ofthe first base station, communicating with the IP layer of the secondbase station to coordinate use of the RF spectrum between the first basestation and the second base station.

(A10) The method denoted as (A9) may further include, at the first basestation, coordinating use of the RF spectrum with the second basestation at least partially based on respective loads on the first basestation and the second base station.

(A11) The method denoted as (A10) may further include, at the IP layerof the first base station, communicating with the IP layer of the secondbase station to coordinate use of the common RF spectrum between thefirst base station and the second base station at least partially basedon a market price of the RF spectrum.

(B1) A method for communicating between base stations of two differentwireless communication networks may include (1) receiving, at anInternet Protocol (IP) layer of a second base station of a secondwireless communication network, a setup request message from an IP layerof a first base station of a first wireless communication network, thesetup request message including a first user equipment (UE) devicecontext format of the first wireless communication network and a secondUE device context format of the second wireless communication network,(2) transmitting, from the IP layer of the second base station to the IPlayer of the first base station, a setup response, the setup responseincluding a union of the first UE device context format and the secondUE device context format, and (3) at the IP layer of the second basestation, communicating with the IP layer of the first base stationaccording to the union of the first UE device context format and thesecond UE device context format.

(B2) The method denoted as (B1) may further include (1) receiving, atthe IP layer of the second base station, a handover request message fromthe IP layer of the first base station, the handover request complyingwith the union of the first UE device context format and the second UEdevice context format, and (2) transmitting a handover confirmationmessage from the IP layer of the second base station to the IP layer ofthe first base station.

(B3) Any one of the methods denoted as (B1) and (B2) may further includeoperating the second base station in radio frequency (RF) spectrumshared with the first base station.

(B4) The method denoted as (B3) may further include, at the IP layer ofthe second base station, communicating with the IP layer of the firstbase station to coordinate use of the RF spectrum between the first basestation and the second base station.

(B5) The method denoted as (B4) may further include, at the second basestation, coordinating use of the RF spectrum with the first base stationat least partially based on respective loads on the first base stationand the second base station.

(B6) The method denoted as (B4) may further include, at the IP layer ofthe second base station, communicating with the IP layer of the firstbase station to coordinate use of the RF spectrum between the first basestation and the second base station at least partially based on a marketprice of the common RF spectrum.

(C1) A method for coordinating a handover of a user equipment (UE)device between respective base stations of two different wirelesscommunication networks may include (1) transmitting a handover requestmessage from an Internet Protocol (IP) layer of a first base station ofa first wireless communication network to an IP layer of a second basestation of a second wireless communication network, (2) receiving, atthe IP layer of the first base station, a handover confirmation messagefrom the IP layer of the second base station, (3) transmitting ahandover command message from the IP layer of the first base station tothe UE device, and (4) at the first base station, relaying dataassociated with the UE device between a first central control device ofthe first wireless network and the IP layer of the second base station,during the handover.

(C2) The method denoted as (C1) may further include (1) determining, atthe first base station, that the UE device would be better served by thesecond base station than the first base station, and (2) transmittingthe handover request from the IP layer of the first base station to theIP layer of the second base station in response to determining that theUE device would be better served by the second base station than thefirst base station.

(C3) In any one of the methods denoted as (C1) and (C2), each of thefirst wireless communication network and the second wirelesscommunication network may operate according to a fifth generation (5G)New Radio-Unlicensed (NR-U) protocol.

(D1) A method for coordinating a handover of a user equipment (UE)device between respective base stations of two different wirelesscommunication networks may include (1) receiving, at an InternetProtocol (IP) layer of a second base station of a second wirelesscommunication network, a handover request message from an IP protocollayer of a first base station of a first wireless communication network,(2) transmitting a handover confirmation message from the IP layer ofthe second base station to the IP layer of the first base station, (3)transmitting a path switch request from the IP layer of the second basestation to a central control device of the second wireless communicationnetwork, the path switch request requesting that the central controldevice transmit data for the UE device to the second base station, and(4) at the second base station, relaying data associated with the UEdevice between the IP layer of the first base station and the UE device,during the handover.

Changes may be made in the above methods, devices, and systems withoutdeparting from the scope hereof. It should thus be noted that the mattercontained in the above description and shown in the accompanyingdrawings should be interpreted as illustrative and not in a limitingsense. The following claims are intended to cover generic and specificfeatures described herein, as well as all statements of the scope of thepresent method and system, which, as a matter of language, might be saidto fall therebetween.

What is claimed is:
 1. A method for communicating between base stationsof two different wireless communication networks, comprising:transmitting a setup request message from an Internet Protocol (IP)layer of a first base station of a first wireless communication networkto an IP layer of a second base station of a second wirelesscommunication network, the setup request message including a first userequipment (UE) device context format of the first wireless communicationnetwork and a second UE device context format of the second wirelesscommunication network; receiving, at IP layer of the first base station,a setup response from the second base station, the setup responseincluding a union of the first UE device context format and the secondUE device context format; and at the IP layer of the first base station,communicating with the IP layer of the second base station according tothe union of the first UE device context format and the second UE devicecontext format.
 2. The method of claim 1, further comprising, beforetransmitting the setup request message: transmitting a configurationtransfer message from the IP layer of the first base station to a firstcentral control device of the first wireless network, the configurationtransfer message including a request for the second UE device contextformat; and receiving a configuration transfer response message at theIP layer of the first base station from the first central controldevice, the configuration transfer response message including the secondUE device context format.
 3. The method of claim 2, wherein theconfiguration transfer message further includes an identity of thesecond wireless communication network.
 4. The method of claim 3, whereinthe configuration transfer message further includes a request for one ormore addresses associated with the second wireless communicationnetwork.
 5. The method of claim 2, further comprising transmitting theconfiguration transfer message from the IP layer of the first basestation to a Mobility Management Entity (MME) of first central controldevice.
 6. The method of claim 1, further comprising transmitting ahandover request message from the IP layer of the first base station tothe IP layer of the second base station, according to the union of thefirst UE device context format and the second UE device context format;receiving, at the IP layer of the first base station, a handoverconfirmation message from the IP layer of the second base station; andin response to receiving the handover confirmation message at IP layerof the first base station, transmitting a handover command message fromthe IP layer of the first base station to a UE device connected to thefirst base station.
 7. The method of claim 6, further comprising, at thefirst base station, relaying data associated with the UE device betweena first central control device and the IP layer of the second basestation, during a handover of the UE device from the first base stationto the second base station.
 8. The method of claim 1, further comprisingoperating the first base station in radio frequency (RF) spectrum sharedwith the second base station.
 9. The method of claim 8, furthercomprising, at the IP layer of the first base station, communicatingwith the IP layer of the second base station to coordinate use of the RFspectrum between the first base station and the second base station. 10.The method of claim 9, further comprising, at the first base station,coordinating use of the RF spectrum with the second base station atleast partially based on respective loads on the first base station andthe second base station.
 11. The method of claim 9, further comprising,at the IP layer of the first base station, communicating with the IPlayer of the second base station to coordinate use of the common RFspectrum between the first base station and the second base station atleast partially based on a market price of the RF spectrum.
 12. A methodfor communicating between base stations of two different wirelesscommunication networks, comprising: receiving, at an Internet Protocollayer (IP) layer of a second base station of second wirelesscommunication network, a setup request message from an IP layer of afirst base station of a first wireless communication network, the setuprequest message including a first user equipment (UE) device contextformat of the first wireless communication network and a second UEdevice context format of the second wireless communication network;transmitting, from the IP layer of the second base station to the IPlayer of the first base station, a setup response, the setup responseincluding a union of the first UE device context format and the secondUE device context format; and at the IP layer of the second basestation, communicating with the IP layer of the first base stationaccording to the union of the first UE device context format and thesecond UE device context format.
 13. The method of claim 12, furthercomprising receiving, at the IP layer of the second base station, ahandover request message from the IP layer of the first base station,the handover request complying with the union of the first UE devicecontext format and the second UE device context format; and transmittinga handover confirmation message from the IP layer of the second basestation to the IP layer of the first base station.
 14. The method ofclaim 12, further comprising operating the second base station in radiofrequency (RF) spectrum shared with the first base station.
 15. Themethod of claim 14, further comprising, at the IP layer of the secondbase station, communicating with the IP layer of the first base stationto coordinate use of the RF spectrum between the first base station andthe second base station.
 16. The method of claim 15, further comprising,at the second base station, coordinating use of the RF spectrum with thefirst base station at least partially based on respective loads on thefirst base station and the second base station.
 17. The method of claim15, further comprising, at the IP layer of the second base station,communicating with the IP layer of the first base station to coordinateuse of the RF spectrum between the first base station and the secondbase station at least partially based on a market price of the common RFspectrum.